A novel and efficient photoredox/copper cocatalyzed domino cyclization of oxime esters, aldehydes, and amines has been achieved, affording a broad range of fully substituted 1H-imidazoles in good yields.
A dual photoredox/copper-catalyzed domino cyclization of oxime esters with TMSCN has been achieved. A range of structurally novel tetrasubstituted pyrazines have been constructed in good yields.
To analyze the flavor components in 17 commercially available wine samples from seven grape varieties (Cabernet Sauvignon, Cabernet Gernischt, Shiraz, Merlot, Pinot Noir, Tempranillo and Chardonnay), comprehensive flavor characterization, volatile and non-volatile compounds of grape wines were evaluated by headspace solid phase micro-extraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS), electronic nose (E-nose), electronic tongue (E-tongue), high performance liquid chromatography (HPLC) and automatic amino acids analyzer. According to GC-MS analysis, a total of 86 volatile compounds were identified, mainly including alcohols, esters, phenols, terpenes and norisoprenoids. Results showed that significant differences of contents of free amino acids and radar fingerprint chart of E-tongue technology were recorded for the 17 grape wines. Moreover, principal component analysis (PCA) of E-nose and E-tongue were used to distinguish the different grape wines effectively, with the cumulative contribution rate accounting for 92.33% and 91.78%, respectively. The results prove that sensors W2S and W1W in the E-nose for wines have a higher influence in the current pattern file. The most abundant phenol in 17 wine samples is catechin. The differences in species and contents of volatile and non-volatile substances give the unique flavor of different grape wines. The results demonstrated that the above mentioned equipment are useful for in-depth grape wine flavor analysis.
Tri- or tetrasubstituted furans have been prepared from terminal activated olefins and acyl chlorides or anhydrides by a multicomponental convergent synthesis mode. Instead of stoichiometric nBu3P, only catalytic nBu3P or nBu3P=O is needed to furnish the furans in modest to excellent yields with a good functional group tolerance under the aid of reducing agent silane. This synthetic method features a silane-driven catalytic intramolecular Wittig reaction as a key annulation step and represents the first successful application of catalytic Wittig reaction in multicomponent cascade reaction.
6 November 2017 in European Journal of Organic Chemistry